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ssh signing: provide a textual signing_key_id

For ssh the user.signingkey can be a filename/path or even a literal ssh pubkey.
In push certs and textual output we prefer the ssh fingerprint instead.

Signed-off-by: Fabian Stelzer <fs@gigacodes.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Fabian Stelzer 2021-09-10 20:07:38 +00:00 committed by Junio C Hamano
parent fd9e226776
commit 4838f62c8c
3 changed files with 66 additions and 4 deletions

View File

@ -24,6 +24,7 @@ struct gpg_format {
int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key);
const char *(*get_default_key)(void);
const char *(*get_key_id)(void);
};
static const char *openpgp_verify_args[] = {
@ -61,6 +62,8 @@ static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature,
static const char *get_default_ssh_signing_key(void);
static const char *get_ssh_key_id(void);
static struct gpg_format gpg_format[] = {
{
.name = "openpgp",
@ -70,6 +73,7 @@ static struct gpg_format gpg_format[] = {
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
.get_default_key = NULL,
.get_key_id = NULL,
},
{
.name = "x509",
@ -79,6 +83,7 @@ static struct gpg_format gpg_format[] = {
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
.get_default_key = NULL,
.get_key_id = NULL,
},
{
.name = "ssh",
@ -88,6 +93,7 @@ static struct gpg_format gpg_format[] = {
.verify_signed_buffer = NULL, /* TODO */
.sign_buffer = sign_buffer_ssh,
.get_default_key = get_default_ssh_signing_key,
.get_key_id = get_ssh_key_id,
},
};
@ -484,6 +490,41 @@ int git_gpg_config(const char *var, const char *value, void *cb)
return 0;
}
static char *get_ssh_key_fingerprint(const char *signing_key)
{
struct child_process ssh_keygen = CHILD_PROCESS_INIT;
int ret = -1;
struct strbuf fingerprint_stdout = STRBUF_INIT;
struct strbuf **fingerprint;
/*
* With SSH Signing this can contain a filename or a public key
* For textual representation we usually want a fingerprint
*/
if (starts_with(signing_key, "ssh-")) {
strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", "-", NULL);
ret = pipe_command(&ssh_keygen, signing_key,
strlen(signing_key), &fingerprint_stdout, 0,
NULL, 0);
} else {
strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf",
configured_signing_key, NULL);
ret = pipe_command(&ssh_keygen, NULL, 0, &fingerprint_stdout, 0,
NULL, 0);
}
if (!!ret)
die_errno(_("failed to get the ssh fingerprint for key '%s'"),
signing_key);
fingerprint = strbuf_split_max(&fingerprint_stdout, ' ', 3);
if (!fingerprint[1])
die_errno(_("failed to get the ssh fingerprint for key '%s'"),
signing_key);
return strbuf_detach(fingerprint[1], NULL);
}
/* Returns the first public key from an ssh-agent to use for signing */
static const char *get_default_ssh_signing_key(void)
{
@ -532,6 +573,21 @@ static const char *get_default_ssh_signing_key(void)
return default_key;
}
static const char *get_ssh_key_id(void) {
return get_ssh_key_fingerprint(get_signing_key());
}
/* Returns a textual but unique representation of the signing key */
const char *get_signing_key_id(void)
{
if (use_format->get_key_id) {
return use_format->get_key_id();
}
/* GPG/GPGSM only store a key id on this variable */
return get_signing_key();
}
const char *get_signing_key(void)
{
if (configured_signing_key)

View File

@ -64,6 +64,12 @@ int sign_buffer(struct strbuf *buffer, struct strbuf *signature,
int git_gpg_config(const char *, const char *, void *);
void set_signing_key(const char *);
const char *get_signing_key(void);
/*
* Returns a textual unique representation of the signing key in use
* Either a GPG KeyID or a SSH Key Fingerprint
*/
const char *get_signing_key_id(void);
int check_signature(const char *payload, size_t plen,
const char *signature, size_t slen,
struct signature_check *sigc);

View File

@ -341,13 +341,13 @@ static int generate_push_cert(struct strbuf *req_buf,
{
const struct ref *ref;
struct string_list_item *item;
char *signing_key = xstrdup(get_signing_key());
char *signing_key_id = xstrdup(get_signing_key_id());
const char *cp, *np;
struct strbuf cert = STRBUF_INIT;
int update_seen = 0;
strbuf_addstr(&cert, "certificate version 0.1\n");
strbuf_addf(&cert, "pusher %s ", signing_key);
strbuf_addf(&cert, "pusher %s ", signing_key_id);
datestamp(&cert);
strbuf_addch(&cert, '\n');
if (args->url && *args->url) {
@ -374,7 +374,7 @@ static int generate_push_cert(struct strbuf *req_buf,
if (!update_seen)
goto free_return;
if (sign_buffer(&cert, &cert, signing_key))
if (sign_buffer(&cert, &cert, get_signing_key()))
die(_("failed to sign the push certificate"));
packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string);
@ -386,7 +386,7 @@ static int generate_push_cert(struct strbuf *req_buf,
packet_buf_write(req_buf, "push-cert-end\n");
free_return:
free(signing_key);
free(signing_key_id);
strbuf_release(&cert);
return update_seen;
}